splice: add SPLICE_F_NONBLOCK flag

It doesn't make the splice itself necessarily nonblocking (because the
actual file descriptors that are spliced from/to may block unless they
have the O_NONBLOCK flag set), but it makes the splice pipe operations
nonblocking.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/splice.c b/fs/splice.c
index 7c2bbf18d7a7c3622679bbf6e6a7f0bc0a78c7fa..6081cf7d2d1ba91c0b5d613904994cdd6876b8b9 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -106,7 +106,7 @@ static struct pipe_buf_operations page_cache_pipe_buf_ops = {
 
 static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
                            int nr_pages, unsigned long offset,
-                           unsigned long len)
+                           unsigned long len, unsigned int flags)
 {
        struct pipe_inode_info *info;
        int ret, do_wakeup, i;
@@ -159,6 +159,12 @@ static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
                        break;
                }
 
+               if (flags & SPLICE_F_NONBLOCK) {
+                       if (!ret)
+                               ret = -EAGAIN;
+                       break;
+               }
+
                if (signal_pending(current)) {
                        if (!ret)
                                ret = -ERESTARTSYS;
@@ -191,7 +197,7 @@ static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
 }
 
 static int __generic_file_splice_read(struct file *in, struct inode *pipe,
-                                     size_t len)
+                                     size_t len, unsigned int flags)
 {
        struct address_space *mapping = in->f_mapping;
        unsigned int offset, nr_pages;
@@ -279,7 +285,7 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe,
         * Now we splice them into the pipe..
         */
 splice_them:
-       return move_to_pipe(pipe, pages, i, offset, len);
+       return move_to_pipe(pipe, pages, i, offset, len, flags);
 }
 
 ssize_t generic_file_splice_read(struct file *in, struct inode *pipe,
@@ -291,7 +297,7 @@ ssize_t generic_file_splice_read(struct file *in, struct inode *pipe,
        ret = 0;
        spliced = 0;
        while (len) {
-               ret = __generic_file_splice_read(in, pipe, len);
+               ret = __generic_file_splice_read(in, pipe, len, flags);
 
                if (ret <= 0)
                        break;
@@ -299,6 +305,11 @@ ssize_t generic_file_splice_read(struct file *in, struct inode *pipe,
                in->f_pos += ret;
                len -= ret;
                spliced += ret;
+
+               if (!(flags & SPLICE_F_NONBLOCK))
+                       continue;
+               ret = -EAGAIN;
+               break;
        }
 
        if (spliced)
@@ -527,6 +538,12 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out,
                                break;
                }
 
+               if (flags & SPLICE_F_NONBLOCK) {
+                       if (!ret)
+                               ret = -EAGAIN;
+                       break;
+               }
+
                if (signal_pending(current)) {
                        if (!ret)
                                ret = -ERESTARTSYS;

diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 75c7f55023ab67912452fad79330dfd36ad59e7c..d218fc72931997685eca76891afaf0c3a3e98730 100644 (file)
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -60,5 +60,8 @@ void free_pipe_info(struct inode* inode);
  * add the splice flags here.
  */
 #define SPLICE_F_MOVE  (0x01)  /* move pages instead of copying */
+#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
+                                /* we may still block on the fd we splice */
+                                /* from/to, of course */
 
 #endif